If your are overpowered then your massive weight could snap the fin. For optimum performance in this potentional hazardous state you should have a steel fin., sizes 46-48 will still probably break as your load is something found on the axel of a race car. something smaller will deliver tons of spin out for bulk but wont break.
Stock fins are made for people who don't live at Mcdonalds. They are for people who concider their day to day well being and are in fact excellent for that type of healthy minded person.